Apparatus for perforating casing



Original Filed June 19, 1953 y 1957 T. L. LONG 2,799,224

APPARATUS FOR PERFORATING CASING h 4 Sheets-Sheet l INVENTOR. THOMAS A. LG/V July 16, 1957 T. LONG 2,799,224

APPARATUS FOR PERFORATING CASING Original Filed,June 19, 1953 4 Sheets-Sheet 2 FHE 3 IN VEN TOR. THOMAS A. LONG BY WWW July 16, 1957 T. 1.. LONG APPARATUS FOR PERFORATING CASING Original Filed June 19, 1953 4 Sheets-Sheet 3 INVENTOR. 77/0/1445 L. L0/V6 FIE-7 July 16, 1957 T. 1.. LONG APPARATUS FOR PERFORATING CASING 4 Sheets-Sheet 4 Original Filed June 19, 1953 1 t I J INVENTOR. THUMAJ L- LOIVG tates nite 2,799,224 APPARATUS FOR'PERFORATING=CASING-- Thii1as;L..Long,.Houstou, Tex., assignor,-by mesneassiguinents, to Joimston Testers, Inc.', Houston, Tex.,. a corporation of Texas Continuation oiiapplication Serial No. 3.,62,889j,v.iune 1.9, r.

1953 ,Thisiappli cation January. 25, 1954', SeriaL'No. 406,020.,

3 Claims .(Cl. Idle-20) This, invention relatesto apparatus for perforating well casing; and; particularly, to an improved :apparatus by which; detonablercharges may be lowered to a.desired depth and discharged for perforating the casing; of a-Well.--; This application relates to and is ,a-continuationof my application Serial No. 362,889 filed June 19, 1953, now abandoned.

During the drilling, testing, and completing .of wells,

and for variousoperations relating thereto. it is frequently. desirable for various reasons to perforate a well casing :at adesired depth, to permit the flowof fluid between the surrounding formations and the casing at that depth. For

example, it is: often. desirable, when completinganwell, to perforate the casingto admit oil or gas into the casing from surrounding strata of aproductive character-. Also,

it is frequently desirable to perforate the casing-atvarious levels. for .test, purposes.

materials such as cement, acidizing -mixtures, or other flowablematerial may be forced outwardly from the easing into strata through which the Well has been drilled. The length ofcasing to be perforated, and the spacing and pattern of the perforations along such length, varies widely in accordance with the depth of the strata involved.

Similarly, .it may be desirable v to perforate the casing at. predetermined levels .so that and the purpose for which the perforation of the casing is desired. ,Thus, in completing a well for production purposes, it may be desired to perforatea'length of casing approximatinggthe thickness of a productive strata, with perforations relatively closely spaced vertically along the casing and with the perforations opening outwardly in angularly spaced relation so as to admit oil or gas from all sides of the casing. For testing purposes-however, it may be desired to perforate only within a limited length of the casing. --The vertical spacing ofperforations may vary through any desired range, and may be great or small, depending uponprevailing conditions and-the purpose for which the casing is to be perforated.

Usually it is desirable to perforate the length ofcasing in the pattern required for a-particular purpose at-a singleoperatiomso, astoavoid the time and expense of running in the perforating apparatus repeatedly. Usually it -is" desirable to withdraw the equipment from the well, after the perforating-operation, for tutu-reuse.

In that case, apparatus made-of metal, which is relatively-strong,-lrard andrheavy is required. The "rigidity of suchapparatus makes it diflicult to lower the apparatus pastbends or obstructions encountered in the well. sharp bends-often encountered in wells have heretofore The relatively seriously limited the length of perforating apparatus which maybe forced therepast, and has objectionably increased the time, labor, and expenseof the perforating operation. It is among the objects of the present invention to provide-a-perforating'apparatus whereindetonable charges are positioned at intervals along a unit made up of any,

desired number of links joined to produce a required length, and which is sufficiently flexible topermit it to be lowered past relatively sharp bends without damaging the perforating charges or the apparatus,

Patented July 16, 1957 ice Another object is to provide a perforating unit m'ade up :of anyzdesirednumber of pivotally connected'linkshaving chambers provided at intervals: therealongto' receiveoperforatingrmeans, of either the projectile 'or the shaped :chargetype, which maybe detonated to perforate the casing along any desired length.

A further object is to provide. a.perforating device in which pintles pivotallyinconnecting adjacent links are utilized;;to; provide: chambers .for detonable charges, dischargeableto perforate. a vwell casing at points in axialalignment witlrthev pintles, and-.which permit-the links to be rolled 'into ia:compact .-form for storage-or trans-- portation'. I

Another objectisto provide asperforating device in which-the perforatingxcharges are positioned to perforate a casing;at angularly as'welli'as vertically spaced points= along any .desiredilengthi of casing.

It is; a-furtherrobjectof the invention to provide a flexible u'nit made up of links interengageably"connected by pintles, andhavingpairs of linksspaced a desired dis- I 1 tanceiaapart by spacers of selected length interlockinglycngaging the links:

It is also 'an object of the invention to provide an arrangementein whicha desired plurality of detonable perforating ichargesimay be detonated by a prim'acord' twinedsalo'ng; the flexibly joined links of a carrier, to perforate; a: casing Lzin a:desired pattern along a desiredlength: of the teasing.

Further objects includeirnproved features of construction-"rand rmode; of .operation affordingincreased adaptability}: operative efficiency; and simplicity and :economy in manufacture; assembly; and use.

The invention-:has otherobjects and"fe'atures of advantage; some ECfWhlCh with the foregoing wilhbe ex- 1 plain'edyin the'following description of those embodi-"f mentsrrof the fi'invention iselectedfor illustration in the drawings; .'It is to be understood that the invention is not limitedptothe particular embodiments shown-in the drawings,=-as it may-be otherwise 'embodied within the definition of the claimsnr.

In thedrawingszi Fig.5 l: is a: fragmental side: elevational view of J a per- 1 foratingi unitaembodying. the invention! Figx2 is a fragmental:sideelevationalview'of a pottion'ofaimodified-form of the device'shownin Fig. '1.

iFig23 is'a' fragmental side'elevational view of-another modified iembodiment of: the invention. I

Figx-4zis a perspectivelview of one formof link constructedrin: accordance with the invention. l,

form; of link: '1

Figs. 6'zand 7' are perspective 1 views-= of links of a charactercsuitablefor use with'spacers of selected length; in an arrangement-1 such. as illustrated in Fig. 3 of the made irr:accordancewiththe present inventionv Fig. 9 is a mid-sectional view of a pintle" of the char-' actemcontemplatedaby the present invention chambered to receivesaa detonableperforatingcharge-ofthe shaped Fig. 10 is asimilar; mid-sectional view of another form-""- of pintle having. aperforating charge of the projectile" type positioned; thereimz-t';

Fig. 11 isa;;-fr agme ntal:-z sideelevational view. partly in vertical-section,- illustrating :a modifiedkformiof the" spacer-..means;.&foriconnectinguthe :links' of thepresent invention.-.

Fig. L2 is an explodedjview ;illustrating.a;modified' form-g-;of interlocking: connecting; means useful for con nectingnspacersnbetween adjacent' 'links in' an arrangement, such.asshowrrinfFig lih. s

a-perspective view of another -formof link Fig. 13 is an enlarged section detail view of the modified link structure shown in Fig. 11 of the drawings, the plane of the section being indicated by the line 1313 of Fig. 11'. j Y

Fig. 14 is a sectional detail, the plane of the section being indicated by the line 14-14 of Fig. 13.

Fig. is a fragmental detail view, partlylin section, illustrating the interfitting engagement of links of the type shown in Fig. 5.

In terms of broad inclusion, the casing perforating device of the present invention comprises a plurality of links interconnected to form a unit of desired length for positioning a plurality of casing perforating charges of either the projectile or the shaped charge type, in vertically and angularly spaced relation at a desired depth and between predetermined points within a well casing. Preferably the links are pivotally connected by means of pintles, which engage matching bearing portions formed upon the ends of the links, and which may be of integral structure or comprise separate end pieces connected by spacers of desired length. The pintles are axially chambered to receive the perforating charges. The wall portion of the pintle, in which the charge is seated, is reinforced by the interfitting bearing portions of adjacent links, so as to provide adequate strength in a unit of relatively light weight and compact form. Any number of links may be joined together to form a unit designed to meet any specific requirement, and which may be made to supply whatever flexibility may be required for different types of service. Provision is made for detonating the perforating charges by means of a primacord twined along the link assembly with portions of the primacord effectively held in detonating engagement with the several charges mounted in the pintles without affecting their flexibility, and insuring an efficient discharge of all the perforating charges regardless of the number, the vertical spacing, and the angular arrangement of perforating charges along the assembled unit. It is a feature of the invention that the links may be assembled with or without spacers at the time and place of use; or units of appropriate type may be assembled at a central shop, where they may be rolled into compact form for storage and transportation to a distant point for use.

In terms of greater detail the perforating device of the present invention comprises a plurality of links 1 pivotally connected by means of pintles 2 engaging interfitting bearing portions 3 and 4 formed upon adjacent ends of adjacent links. As illustrated, each pivot joint comprises a portion 3 of single thickness shaped to interfit with a bifurcated portion 4 upon the end of an adjacent link 1. Bearing openings 5 are formed in the portions 3 and 4, and are arranged to register to receive pintles 2 by which the links are held in assembled pivoted relation. In the form illustrated in Figs. 1, 2, 4 and 5, each link is an integral unit having a single bearing portion 3 at one end and a bifurcated bearing portion 4 at the opposite end. The portions 3 and 4 are so designed that the single thickness 3 of one link will interfit in matching relation with the bifurcated bearing portion 4 of an adjacent link to receive a pintle 2 by which the links are pivotally connected.

The links 1 may be made of various kinds of material depending upon the service for which they are intended. For many types of service, it is desirable to Withdraw the apparatus from a Well, after a perforating operation has been completed, for subsequent use at a different depth in the same well, or in a different well. For such service, the links are preferably made of steel, iron, or other hard and strong metal adapted to withstand long hard usage. Where light weight is a desirable factor, the links may be made of aluminum, aluminum alloys, or other similar materials conducive to that quality. Sometimes it is preferred to use a unit of destructible character intended for only, a single use. For such purposes, the links may be made of plastic, or other frangble material, adapted'to be broken into fragments when the perforating charges are detonated. The fragments may either be left in the well, or they may be further broken up and removed from the well in the course of a subsequent drilling operation.

The pintles 2 are of a hollow cylindrical shape having a flange 6 at one end forming a shoulder 7 arranged to seat against an outer face of one of the bearing portions 4 of each joint. The pintles are shaped to fit closely within the openings in the bearing portions 3 and 4 to provide pivot pins about which the links may be pivotally moved. Each pintle 2 is preferably provided with an annular groove 10 intermediate its ends. The groove 10 is arranged to be engaged by the inner end of a set screw 8, threaded through the bearing portion 3 of an adjoining link, for holding the pintle against axial movement without materially limiting the pivotal movement of the connected links.

The hollow central portion of each pintle 2 forms a chamber arranged to receive a detonable charge of a character adapted to perforate the surrounding well casing at a point opposite the axis of the pintle 2. The detonable charge may be of the shaped charge type 9, as shown in Fig. 9 of the drawings; or it may be of a projectile type, as illustrated in Fig. 10, having a charge of explosive material 11 arranged to force a solid projectile 12 outwardly from the chamber of the pintle along the axis of the pintle when the charge 11 is detonated.

In the case of a shaped charge 9, the charge is preferably positioned in the hollow central chamber of the pintle as illustrated in Fig. 9. The front of the chamber is preferably closed by a wall portion 13 of relatively reduced thickness through which the force of the charge 9 is effective for perforating the well casing at a point opposite the charge. In this arrangement the rearward end of each pintle is covered by a closure plate 14, firmly seated in the end of the pintle 2 over a gasket 15, for sealing the charge within the chamber. The end plate is provided with a firing duct 16, which extends axially through the end plate, and through which the charge may be detonated by a suitable exploding means, such as a length of primacord 17 positioned over the outer end of the firing duct.

As illustrated in Fig. 10, the chamber of the pintle opens through the front of the pintle. The explosive charge 11 is placed in the back of a projectile seated in the front end of the chamber. A gasket 18 seals the charge in the back of the recess and provides a seat for the projectile. The front of the chamber is closed by a closure disc 19, which is displaceable by the projectile when the charge is detonated. Here the firing duct 16 is axially positioned in the back wall of the pintle 2, which in this case is integral with the pintle 2 instead of being a separate plate as indicated in Fig. 9. The structure of the pintles 2 may of course be modified in numerous ways to accommodate detonable charges of different type, form, and size, in accordance with varying requirements.

The links 1 may be constructed in various ways to meet various requirements. In Fig. 1, I have illustrated a construction wherein the links 1 are of relatively short length and have the single bearing portion 3 closely coupled to bifurcated bearing portions 4 at the opposite end of the link. The axis of the opening 5 in the bearing portion 3 is disposed at approximately right angles to the axis of the bearing portion 4 so that the perforating charges will be directed outwardly in directions angularly spaced about apart. Any number of the links may be connected together to form a unit of desired length in which each pintle will include the firing chamber for a perforating charge. The charges are of course spaced vertically in accordance with the length of the links, and are angularly spaced in accordance with the angular position of the hearing portions 3 relative to the bearing portions 4. The uppermost link 1 may be pivoted to a connecting link 21 arranged to be secured to the lower end of a. firing head coupling 22 connected to or forming a part of a firing head of any. appropriate character, not illustrated.

Theprimacordl7 extends downwardly from the firing head .through the coupling 22,, and through the connecting member 21 from which it emerges through an opening 23. The primacord 17 is twined around the con-.

nected links of the unit to pass over the outer end of the flring'duct 16 of each pintle 2, as shown in the drawings; The sectionof primacord. 17 passing eachfiring duct is'held in operative position thereoverby means of a boss24 formed on the outer; face of one of, the arms of the bifurcated 'bearingporti0ni4of eachlink, and provided with an inwardly disposed lip 26 under which the i ward the casing-in'aspiralpattern, and the primacord will be twined over the links with minimum distortion.

The-links 1 maybe formed with-wounded ends 27,

concentric with the bearing openings 5, to permit relative movement past correspondingly shaped surfaces at the back of the bifurcatedbearing portions 4 of adjacent links, .as best indicatedin Figs, 4 and-14 of the draw-' ings. This structure permits arelatively wide range of pivotal movement of eachlink relativeto the adjacent link's1about the pintles 2.by which they are connected.

This-pivotal movementaffords flexibility'along the length of the unit such as to permit the unit to pass relatively sharp-bends ,in. a casing as theunit is lowered into a well. The angularrelation of the pintlesxat opposite ends of the rlinkstpermits theunit .to be flexedtto a substan--- tially spiral-form... Thus, a long length ..of the unit can be moved past a. succession :of bends,. disposed at different angles,,along.ar-longlengthpf casinglto reach-a desired depth, the unit .itself being..of. sufficientnlength to extend through a strataof. substantial thickness. Also,

the unitnmay be rolledinto arelatively. compact. .roll, as it is being assembled, whereby'it maybe stored and v.

transported conveniently and within-a minimum of space.

At the lower end of the assembled unit, a nose piece 23 having a roundedlower..-facez 25? maybe mounted to provide a feelerby which the lowerend of the unit may be guided past obstructions or turnsin the well casing. The primacord 17 maybe extended through .an

opening in the nose piece 28 where it may be knotted, or otherwise secured against displacement as the unit. is lowered along a well casing.

In some-cases, it is desired to have the unit held rela-. tively rigid along part or all ofthe length thereof. Where such rigidity is required-the links may be provided with a squared end 31 engageable with a correspondingly squared seat at the back of the adjacent bearing portion 4, as indicated in Figs. 5 and 15. The squared end 31 may seat closely against the seat 32, and thus produce a substantially rigid structure at the joint by which two links are connected. If a limited amount of flexibility is desired, the space between a squared end 31 and its opposing seat 32 may be varied to afford a desired degree of flexibility, and at the same time prevent flexing of the unit beyond the desired limits. By appropriate selection of links, the assembled unit may be made rigid at some joints and flexible at other joints along its length.

Figs. 2 and 8 illustrate a modified form of link in which a chambered portion 33 is formed intermediate the bearing portions 3 and 4 to receive an additional perforating charge placed therein and dischargeable coincidently with the charges in the pintles 2 at the pivoted ends of the lengths. In this illustrated arrangement, the axis of the portion 3 is positioned parallel to the axis of the bearing portion 4, and the chambered portion 33 is disposed at an angle of about 90 relative thereto. The distance between the bearingportions Sand 4 and the intermediate chambered portion 33 inayof course be variedthrough wide limitsfor spacing the perforating charges along the lengthof each unit and along a unitof assembled links. Similarly, the angular relation may he varied as desired;

The web portions 34 which join the beariugportions to i the chambered portion 33 preferably have openings 35 to reduce. the weight of each linlc. In the illustrated arrangement,- the assembled unit is flexible in only one direction. The degree of flexibility; of course, vcan be controlledby the use, of links having. squared ends 31 as above, explained; and flexibility in spiral fashion. may be obtained"byalternatingthe links with'links of the form shown in Figs. 4' or 5.

Sometimes it isdesirableto'perforate the casing only at relatively widely spaced' points. In such cases, the

single and bifurcated bearing portions '3 and 4 may be formed as separate units'arranged to be connected by a spacer 37 connecting the-bearing portions in relatively widely spacedrelation, as indicated in Fig. 3 of the drawings. The spacers 37 are preferablypf tubular construction, and of any desired length. 'The ends of the spacers=37 maybe threaded into boxes 38 formed upon the bearing portions 3 and 4-, as indicated-in Fig; 3 of the drawings.- In suchan arrangement, openings 39 may be formed at a point between the bearing portion 3 or 4 and the box portion 38 ofeachlink so that the primacord 17 may extend through the spacer between adjacent joints;

and be extended outwardlyto overlie the firing duct of the pintle by which adjacent joints are pivotally connected.- 1ri this larrangementa continuous length of primacordlal extendsthrough the several spacers 37, and is looped outwardly through the opening'39 for engagementby the bossesr-24 upon the bifurcated bearing por-- tions.4, as indicated in Fig; 3:.o-f. the drawings.

Fig. 1.1 illustrates almodified'arrangement of the means for connecting the interengaging linkz-sections3 and 4 of adjacent joints.

connected to the linklmembers. and/or to eachother, as best indicated. by.Figuresl1 and 12.

along the unit. Thus, instead'of using a continuous length of primacord..-extending along the entire'length of the unit, the primacordisdividedinto separate sections eachconnectingone link to the next adjacent link. In this arrangement the .upper'end of each length of primacord is wrapped around .the firing charge carried by the pintle- 2 connecting two adjacent link portions. The cord 17 is seated .withinan annular groove 43 formed within the bearing portion 3.0f azlink, and is extended downwardly through. the .link:or spacer .connected thereto; as bestillustrated ,in1Figs.--13. and 14. of the drawings. @At its lower--- end, each section of primacord 17 extends downwardly through an opening 44 and into engagement with the boss 24 of the next lower joint, as best illustrated in Fig. 13 of the drawings. The detonation of each perforating charge within a pintle 2 fires the primacord which is looped around the pintle and charge seated therein, so as to detonate the next succeeding perforating charge along the assembled unit. In this manner, the detonation of each perforating charge serves to transmit its detonating action to the next succeeding perforating charge progressively along the unit. Also, this permits short lengths of primacord to be assembled with the links and spacers as they are being joined to form a unit of desired length and spacing, and obviates the inconvenience and risk of handling a continuous strand of primacord of a length sufficient to reach from one end of the unit to another.

In operation, a unit of desired length, having desired flexibility at all or any of the joints thereof, may be readily assembled from standard parts at the well, and

In this arrangement, interconnecting links maybe connected by spacers.37, having 'interengaging keys 41 and keywaysa42, by whichtthe-spacers may be 1 at the time of use, from parts of standardized construction. By an appropriate selection of single links such as shown in Figs. 4 and 5, or double links such as shown in Fig. 8, or separate link members such as shown in Figs. 6 and 7 joined by appropriate spacers 37, the unit can be prepared in conformity with the immediate requirements of each job to perforate the casing at desired intervals along a desired length of the casing. The perforating charges are effectively housed within the pintles by which adjacent links are pivotally connected, and are so positioned by the pintles that the perforating charges will be directed axially of the pintles at right angles to the wall of the casing to insure a maximum perforating action, and with the perforations spaced vertically and angularly in accordance with a predetermined pattern. The interfitting bearing portions 3 and 4 of adjacent links, when made of iron, steel, or other hard strong material prevent radial rupture of the pintles, and preserve the unit in its assembled form for withdrawal from the well and for subsequent use as required.

When it is not desired to recover the unit, the links may be made of plastic or other frangible material, having sufiicient strength to adequately support the perforating charges as they are lowered to a desired position in the casing, but sufliciently fragile to permit them to be broken into fragments by the detonating of the perforating charges. If necessary, the fragments can be further broken up and removed from the well by drilling and related operations at a subsequent time.

By mounting the perforating charges in the pintles of the joints by which successive links are connected, the unit may be made of relatively light Weight andsmall bulk, and of flexibility suited to the needs of each particular job. Similarly, the pintles 2 with their perforating charges may be readily manufactured and stocked for use in making up new units or reloading used units as required.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. In a perforating device for well casing, a hollow link having bifurcated bearing portions upon one end and a single bearing portion upon the opposite end, the single portion of said link being adapted to interfit with the bifurcated portions of an adjacent link, pintles carried in said bearing portions and adapted to pivotally connect said link to adjacent links, said pintles being chambered to receive means detonable to perforate a casing, said single bearing portions having a circumferential groove encircling the pintle for holding primacord in detonating relation with the detonable means in said pintle, said bifurcated bearing portion having a lip upon the outer end for holding primacord in detonating relation to the detonating means in the pintle carried by said bifurcated bearing portion, and a length of primacord carried in said groove, extending through said hollow link and received in said lip.

2. A perforating device for well casing comprising a plurality of links each having axially spaced annular bearing portions upon one end and a single annular bearing portion upon the opposite end, said bearing portions at said one end and at said opposite end having their axes transverse to the longitudinal axis of the link and angularly disposed with respect to each other, the single portion of one link being arranged to interfit with the spaced portions of an adjacent link, means on the interfitting bearing portions for projecting into the bore defined thereby, a pintle retained in said bore by said projecting means and pivotally engaging the interfitting bearing portions of adjacent links, said pintle being provided with a chamber arranged to receive means detonable to perforate a casing, and lip means carried by one of said spaced bearing portions and extending across one end of said bore at an acute angle with respect to the longitudinal axis of the corresponding link for defining a spiral path about said links for detonating cord positioned in detonating engagement with said pintle.

3. A perforating device for Well casing comprising a plurality of links each having a pair of axially spaced annular bearing portions upon one end and a single annular bearing portion upon the opposite end, said bearing portions at said one end and at said opposite end having their axes transverse to the longitudinal axis of the link and angularly disposed with respect to each other, the single portion of one link being arranged to interfit with the spaced portions of an adjacent link to define a bore, a pintle in each said bore pivotally engaging the interfitting bearing portions of adjacent links, each said pintle being provided with a chamber arranged to receive means detonable to perforate a casing, a lip portion carried by one of each pair of said spaced bearing portions and defining an inwardly opening recess extending across one end of the corresponding bore at an acute angle with respect to the longitudinal axis of the corresponding link, and detonating cord received within each said recess and positioned in detonating engagement with the respective pintle, the recesses on successive links defining a spiral path about said links for said detonating cord.

References Cited in the file of this patent UNITED STATES PATENTS 2,026,061 Prikel Dec. 31, 1935 2,302,595 Berry Nov. 17, 1942 2,422,898 Hendley June 24, 1947 2,616,370 Foster Nov. 4, 1952 2,629,325 Sweetman Feb. 24, 1953 2,664,158 McKean Dec. 29, 1953 2,708,408 Sweetman May 17, 1955 

